Shielded Variable Capacitor Bank for Accurate RF Characterization
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Solution Overview
Problem
Conventional variable capacitor banks in impedance matching systems face challenges in accurate characterization due to interactions with other reactive elements, leading to unpredictable changes in reactance and complex characterization methods, which are impractical and costly.
Innovation Solution
A variable capacitor bank with a grounded conductive housing and multiple capacitor modules sharing a bus, each with switched capacitor branches and an unswitched 'floor' capacitor, is designed to minimize interactions with other elements, using a single port configuration for improved isolation and characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional variable capacitor banks are used in impedance matching systems, then capacitance adjustment is achieved, but interactions with other reactive elements cause unpredictable changes in reactance and inaccurate characterization
Solution Approach 1:
The patent extracts the variable capacitor bank from the complex electromagnetic environment by providing a separate housing that physically isolates the capacitor modules from other reactive elements like inductors. This extraction eliminates the harmful electromagnetic interactions that caused unpredictable reactance changes, enabling accurate characterization of the capacitor bank's electrical characteristics.
Solution Approach 2:
The housing acts as an intermediary barrier between the variable capacitor bank and other reactive elements in the impedance matching system. By introducing this intermediate structure, the patent blocks electromagnetic field interactions while still allowing the capacitor bank to perform its intended function of adjusting capacitance for impedance matching.
2Adaptability or versatility
If multiple capacitor modules are used to achieve variable capacitance, then capacitance range is improved, but device complexity and difficulty of characterization increase
Solution Approach 1:
The patent merges multiple capacitor modules into a single integrated variable capacitor bank with a unified housing and shared electrical connections. This combining approach maintains the capacitance range provided by multiple modules while reducing overall device complexity and simplifying characterization by treating the assembly as a single electrical component.
Solution Approach 2:
The housing serves multiple functions simultaneously: it provides structural support for the capacitor modules, acts as an electromagnetic shield to isolate the modules from external fields, and provides a compact enclosure that simplifies integration into the impedance matching system. This multi-functionality reduces the need for additional components.
3Measurement precision
If capacitor modules are isolated from other elements, then characterization accuracy is improved, but device design complexity increases
Solution Approach 1:
The housing is designed to perform multiple functions: providing structural support for the capacitor modules, acting as an electromagnetic shield to isolate the modules from external fields, and serving as a compact enclosure for integration. By combining these functions into a single component, the patent achieves effective isolation for accurate characterization without significantly increasing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables accurate and reliable characterization of variable capacitors by reducing the influence of other elements, allowing for precise impedance matching and capacitance control, thereby improving the efficiency and accuracy of impedance matching in RF applications.
Implementation Method 1
a first variable capacitor bank comprising a first plurality of capacitor modules arranged in parallel and disposed within a first conductive housing that provides electromagnetic shielding of the first plurality of capacitor modules from external electromagnetic fields
Implementation Method 2
Each capacitor module may include a first switched capacitor branch including a first capacitor and a first switch element in series with the first capacitor
Data Source
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AI summary
A variable capacitor bank includes a conductive housing and a port extending through the housing. An electrical bus is disposed within the conductive housing and coupled to the port. The variable capacitor bank further includes capacitor modules disposed within the housing. Each capacitor module includes a module input electrically coupled to the electrical bus and a switched capacitor branch electrically coupled to the module input, the switched capacitor branch including a capacitor and a switch element in series with the capacitor. In certain implementations, one or more of the capacitor modules may include at least one second switched capacitor branch. The capacitor modules may further include an un switched, or "floor", capacitor that provides a minimum or otherwise known capacitance of the capacitor module. Each capacitor module may further be grounded by being electrically coupled to the conductive housing.